Gymnasiums weight rooms, fitness centers, sports training centers, and other areas where weight training equipment is used have traditionally maintained one or both of two broad categories of weight-training equipment. Free weights, the first category of equipment, includes such well-known devices as dumbbells and barbells. Free weights are preferred by many athletes and weight-training enthusiasts because such devices allow full, natural movement during exercise. Since the movement of such devices are fully controlled by the user, these movements are dictated by the natural, curving movements of the human body. For example, a user performing a curl with a dumbbell may begin from a position with the dumbbell held directly below the shoulder with the arm extended downward. From this position, the user bends his or her arm at the elbow, which brings the dumbbell upward in a natural, curving movement. Finally, the dumbbell may be brought to rest against the user's chest and upper arm. During such a movement, the user need not adjust his or her grip on the dumbbell, because the bar does not rotate relative to the user's hand. In addition, the user's wrist is allowed full movement, providing for a graceful, curved, natural motion during exercise.
Although free weights allow a full range of movement during exercise, they do possess certain disadvantages. The primary disadvantage is a lack of convenience. Most dumbbells are constructed to have a certain amount of weight, and thus when a user wants to change the amount of weight, the user must switch dumbbells. This usually requires the user to return the dumbbell being used to an equipment rack, select another dumbbell, and then return to the exercise area. Other dumbbells are constructed so that the user may adjust the weight by either substituting weighted plates of different sizes, or by attaching additional plates. With these dumbbells, the user must remove the locking mechanisms (typically a collar) on each end of the bar, remove the already attached weighted plates if required, attach the desired weighted plates, then reattach the locking mechanisms. With either type of dumbbell, the process of changing the amount of weight used is time-consuming and laborious. This is particularly a problem when a number of users are taking turns using a single piece of equipment, since each user's natural abilities and skill level may require a different amount of weight for a given exercise. A common example of this problem is a football team; an appropriate amount of weight for a particular exercise may vary considerably between the large, strong linemen and the more nimble but less muscular receivers.
To provide greater convenience for multiple users, a second category of weight training equipment developed, known as "stack-loaded" or "selectorized" equipment. Such equipment employs a stack of weighted plates that are connected by cables and pulleys to handles that the user may grip. By moving the position of a pin within the stack of weighted plates, the user may easily and quickly manipulate the amount of weight employed for a particular exercise. This is particularly convenient when a number of users are taking turns at a single piece of equipment, since each user needs simply to move the pin to the amount of weight desired for the particular exercise. Such equipment largely solves the problem of inconvenience created by multiple users of varying skill and strength taking turns with a particular piece of equipment. The disadvantage of selectorized equipment, however, is that the movements employed in the use of such equipment are rigid and unnatural, and make it difficult for the user to isolate particular muscles or muscle groups for development. For example, performing a bench press exercise on a selectorized bench press or "universal" machine would require the user to push up on a bar while gripping the bench press bar with both hands. The bar may be connected through a cable and a series of pulleys to a stack of plates. If, as is often the case, the user has one arm that is stronger than the other, the user's weaker arm will be allowed to simply follow the stronger arm, and perform little of the work during the exercise. Thus such equipment does not allow the user to easily isolate particular muscles or muscle groups during exercise. Selectorized equipment also tends to force movement along straight lines, rather than along natural curves that mimic the natural movements of the human body. These straight lines simplify the design and construction of selectorized weight equipment, but also serve to reduce the user's ability to efficiently target particular muscle groups for development.
Another disadvantage experienced by the user exercising with selectorized equipment is that the user often must readjust his or her grip as the bar moves during each repetition of an exercise. This problem results from the fact that the bar typically does not turn with the user's hand as the exercise is performed. A dumbbell bar, on the other hand, naturally turns as the user's hand turns, and thus a firm grip may be maintained through the entire movement. This limitation of selectorized equipment also contributes to the sensation that exercise with such equipment feels less natural.
To partially address these limitations, selectorized equipment has in part been replaced in recent years with plate-loaded equipment. Instead of using stacked plates that are manipulated through cables and pulleys, plate-loaded equipment uses weighted plates with holes in the middle that are individually added or removed to the equipment using spindles. These plates may be similar to or identical to the plates used on some dumbbells and barbells. This approach allows greater flexibility in equipment design, and improves the ability of the equipment to isolate particular muscle groups during exercise. While not as convenient as selectorized equipment, plate-loaded equipment may be constructed to more closely follow the natural movements of the human body, and produce more comfortable and natural exercise routines. By adding or removing weight plates, the user can vary the amount of weight on a piece of plate-loaded equipment in much the same way as the user changes the amount of weight on a barbell or dumbbell.
Traditional weightlifting plates, or "weight plates," that are used on barbells, dumbbells, and plate-loaded equipment, are shaped as large, flat discs with a hole in the middle. Weight plates are generally designed primarily for attachment to a dumbbell or barbell bar. The plates slide onto one end of the bar through the hole, possibly in addition to other plates added on that end of the bar, and then are fastened into position by a bolt, collar, or some other locking means. By adding or removing weight plates of different sizes, the user may control the amount of weight on the bar. In this way, the user is offered greater flexibility in the type of barbell or dumbbell exercises performed, and may tailor the weight chosen to the user's relative strength and weight-training goals without owning a multitude of dumbbells or barbells of different sizes. In gymnasiums and other facilities having both free weights and plate-loaded equipment, weight plates may be used on either type of equipment, since they may easily be removed from a barbell bar, for example, and then mounted onto the spindle of a piece of plate-loaded equipment. This allows the gym owner to avoid the purchase of expensive but duplicative equipment.
A third method of using weight plates is as a stand-alone training or exercise device. In particular, the "Olympic" style weight plates, which are typically quite large and constructed of iron, have been somewhat popular in years past for this purpose. These devices offer the user certain flexibility in the choice of training regimen that may not be available if only barbells and dumbbells are used. For example, a user may hold an Olympic plate against the user's abdomen during sit-up exercises to more quickly build muscle mass in the user's abdominal area. A dumbbell having similar weight would be far more bulky and unwieldy for this particular exercise. The prior art contains examples of weight plates that are designed to be particularly suited to stand-alone use; U.S. Pat. No. 5,692,996, to Widerman, discloses one such example.
Using a traditional weight plate as a stand-alone exercise device may create significant safety concerns. The only practical way for the user to grip such plates is for the user to hold the plate at the edges. This type of grip may be quite difficult or unsteady, depending upon the weight of the plate, the thickness of the plate, whether a thicker rim extends around the edge of the plate, the strength of the user's grip, and the size of the user's hands. In addition, as the user moves through various exercises, the user may need to change his or her grip position on the plate, which is especially difficult because the user is only holding the edge of a heavy plate. The risk of dropping such a plate during exercise increases each time the user is required to change grip positions. Also, the iron surface of an Olympic weight plate is relatively slick, which is only exacerbated when the user perspires through the course of an exercise routine. These same problems occur when the user is changing plates on a dumbbell or barbell bar, or even when the user is changing weight plates on plate-loaded equipment. In each case, maintaining a firm grip on the plate is a significant safety concern.
One proposed solution to the problem of securely gripping a weight plate is to add elongated holes through the surface of the plate. The user may then place his or her hands through the holes to grip the weight plate. U.S. Pat. No. 5,137,502 to Anastasi, and design Pat. Nos. 355,007 and 409,695, both to Rojas et al., disclose several such weight plates. In addition, commercial examples of such plates are now produced by the Irongrip Barbell Company of Fountain Valley, Calif. These plates have two or three holes through which the user may place his or her fingers, with the user's thumbs remaining on the side of the plate facing the user. If the plate is small enough, the user may place his or her fingers through one hole, and his or her thumb through another hole. Utilizing either of these gripping techniques, the plate may be held more securely because the user's hands actually extend through the plate. These designs reduce the risk of the user's hands slipping from the plate, since the fingers are "captured" to some degree within the holes passing through the plate.
Plates having elongated holes to receive the user's fingers may also facilitate certain types of exercises not possible with traditional weight plates. For example, the user wishing to perform a one-handed curl with a traditional plate would find it difficult to grip the plate in such a manner as to make this exercise possible. If the user gripped the plate along the edge, which is the only practical means of gripping a traditional weight plate, the user's grip would necessarily be somewhat precarious as the plate is raised. By contrast, a weight plate with elongated holes to receive fingers would allow the user to keep a more secure grip on the plate while bending the elbow and raising the plate toward the user's armpit. While this type of exercise is not a traditional curl, and would not follow the natural movements of the human body as a dumbbell curl would, the grip of the user would be more secure than that held along the edge of a traditional weight plate during such an exercise.
It would be difficult if not impossible to perform a full, traditional curl using such a weight plate, since as the user raises his or her hand toward the chest, and the wrist rolls inward, the plate would begin to extend horizontally outward, and away from the user. This problem results from the fact that the back of the user's hand and forearm would press against the plate. Because the user would have little leverage on the plate when it reaches this horizontally extended position, the user may not have sufficient strength to pull the plate up sufficiently to complete a traditional curl repetition. At best, this maneuver would be difficult and uncomfortable for the user. Other exercises would be similarly difficult or impossible because of the inherent limitations of the method of gripping such plates.
These plates with elongated holes also do not provide the user with a solution to the problem of changing his or her grip during each repetition of an exercise. For example, a user performing a traditional one-handed curl with one of these plates would be required to shift his or her grip on the plate as the plate is raised. In effect, the portion of the plate between the hole through which the user's hand is inserted and the rim of the plate must "roll" in the user's palm during this exercise. In fact, these plates may actually increase the severity of the grip-adjustment problem for certain exercises, since it may be more difficult for the user to change his or her grip while the hand is "captured" within a hole in the weight plate than when the grip is simply at the outer edge of a traditional Olympic plate. The user must necessarily release his or her grip on the weight plate somewhat in order to adjust his or her grip position, and thus the risk that the user will drop the plate increases. Also, constantly adjusting one's grip during repetitions of a particular exercise is uncomfortable for the user, reducing the user's willingness to continue the exercise and thereby reach the user's weight-training goals. This same problem is encountered as the user lifts such a weight plate to place it on the spindle of a piece of plate-loaded equipment. Thus a weight plate that both provides a more secure grip and does not require that the user shift his or her grip position during each repetition of an exercise or loading is desired.